By Michael Peltier

TALLAHASSEE, Fla., Sept 25 (Reuters) - A conservative advocacy group began running an Internet ad criticizing the Florida Supreme Court on Tuesday, days after the Republican Party started a campaign to sack three justices who rejected efforts to overturn President Barack Obama's healthcare law.

Americans for Prosperity, a conservative group financed by billionaires Charles and David Koch, released the first in an expected series of ads attacking the Supreme Court after the Republican Party of Florida executive committee voted unanimously to target justices Fred Lewis, Barbara Pariente and Peggy Quince.

The justices face a popular vote to remain in office this fall under the state's merit retention law, which was created in the 1970s to insulate the high court from political pressure.

"All three justices are too extreme not just for Florida, but for America, too," the Republican committee said in a statement announcing its upcoming effort.

The ad does not mention the justices by name but attacks the Affordable Care Act, saying the program is expensive and the law has been unpopular.

"That's why many states, like Ohio, gave their citizens the right to vote against it," the 30-second spot says. "Not Florida. Our own Supreme Court denied our right to choose for ourselves. Shouldn't our courts protect our rights to choose?"

A spokesperson for Americans for Prosperity did not immediately return a phone call for comment.

Slade O'Brien, president of AFP of Florida, told the Miami Herald/Tampa Bay Times: "We're not advocating for the election or defeat of any of the justices. What we're attempting to do is call more attention to them advocating from the bench."

In 2010, the three justices joined the majority in a 5-2 decision to reject a state effort to invalidate the heath care reform. Last year, the court also rejected a move by Republican Governor Rick Scott to circumvent the legislature in agency rulemaking.

The Florida Supreme Court has often been at odds with the Republican-led Florida Legislature and a series of Republican governors over the last dozen years.

In 2000, the three judges joined a majority of the court to order Florida election officials to recount ballots in the presidential election between Democrat Al Gore and Republican George W. Bush. That decision was overturned by the U.S. Supreme Court.

CONSERVATIVE AGENDA?

Critics of the recall say the efforts are less about judicial activism and more to do with a conservative Republican agenda.

"Let's make no mistake," said former state Senator Alex Villalobos, a moderate Republican from Miami. "That is what this is all about."

In 2010, voters removed three Iowa Supreme Court justices who were part of a decision that legalized same-sex marriage in the state. It was the first time members of that state's high court had been recalled by voters.

Created in 1976, Florida's merit retention system was an attempt to take politics out of the judicial nominating process following a series of embarrassing imbroglios involving high court justices.

Under the system, appellate judges and Supreme Court justices are appointed by the governor from a list of candidates submitted by a qualifications commission. While the justices do not face elections against rival candidates, voters are asked every six years to retain them.

If a majority votes against them, replacements will be appointed by the governor.

"The short reason why we have merit selection and merit retention for the appellate bench in Florida is that (the Supreme Court) was riddled with corruption all because of the politics that went into how they were selected," said Martin Dyckman, whose book "A Most Dishonorable Court: Scandal and Reform in the Florida Judiciary," chronicled judicial missteps that led to the merit retention system.

Another group, Orlando-based Restore Justice, was formed in August to target Lewis, Pariente and Quince for removal.

And another, Defend Justice from Politics, was established earlier this month to support the judges' retention efforts. The justices themselves have collectively raised more than $1 million to remain on the bench.

"The consequences of this retention election are not just the individual fates of these three justices but the fate for maybe a generation to come of the Florida Supreme Court," Dyckman said.

(Additional reporting by Kevin Gray)

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